This invention relates, in general, to halocarbon films, and more particularly to halocarbon films having other films disposed thereon.
VLSI and ULSI circuitry require multilevel-interconnect structures to improve the speed and functional density of integrated circuits. In these structures, layers of dielectric material are interdigitated with layers of conductive material to electrically isolate the layers of conductive material from each other. Manufacturers of semiconductor circuits have employed a variety of materials to serve as interlayer, as well as intralayer, dielectric films such as silicon dioxide, nitride, spin-on glass, and polyimide films. Dielectric materials are selected based on a number of criteria including a desired dielectric constant, an ability of the dielectric film to adhere to other films, and ease of incorporation into semiconductor manufacturing processes. A more thorough list of desirable properties for interlayer and intralayer dielectric material may be found on page 195 of "Silicon Processing for the VLSI Era," Vol. 2, by Stanley Wolf.
A particularly useful dielectric material for multilayer structures is a polyimide film. Polyimide films offer low dielectric constants and produce relatively planar surfaces. More importantly, polyimide films are easy to deposit and pattern, thus are ideally suited for integration into semiconductor manufacturing processes. Further, polyimide films are inexpensive. Unfortunately, conductive films do not adhere well to polyimide. Motonari et al., in U.S. Pat. No. 5,006,411, entitled "Polyimide Film Having Fluorocarbon Resin Layer," have taught a technique for improving adhesion of a metal to a polyimide film, wherein a fluorocarbon resin is provided over a surface of the polyimide film. However, this technique requires treating a surface of the polyimide film and a surface of the fluorocarbon resin with a corona discharge. In addition, the two films are pressed together with a press roller. The technique requires a substantial mechanical pressure to bond the films, therefore it is somewhat impractical to use in the manufacture of semiconductor devices.
A dielectric material with similar properties to a fluorocarbon coated polyimide film is a halocarbon film. Like the coated polyimide film, halocarbon films have low dielectric constants, promote surface planarization, are easy to deposit and pattern, and are inexpensive. Unlike the coated polyimide film, the halocarbon film is comprised of a single type of film which may be applied in a liquid state. However, upon curing other films are unable to adhere to a surface of the halocarbon film. Accordingly, it would be advantageous to have a method for altering a surface of the halocarbon film to promote adhesion by other materials, particularly conductive materials, that is inexpensive and easily integrated into semiconductor processing techniques.